We've seen all the crazy stuff you'll be able to do in GTA Online, as well as GTA V, but I've yet to see any mention of a UFO. However, according to the leaked achievements for GTA, Rockstar's apparently hidden at least the parts for one in there somewhere. Are we going to be blasting into space?
The full list is available over on Xbox 360 Achievements, but it's chock-a-block full of spoilers, so I won't list them here. There are a load of achievements directly linked to GTA Online, though, so it looks like you'll be busting up online as well as off if you're chasing 100 per cent completion. [Xbox360Achievements via Kotaku]